Succession is the series of gradual changes that occur in an ecological community over a particular period of time. Ecological succession is of two types;
1) Primary succession, in which a newly exposed or newly formed rock surface is colonized by living organisms for the very first time. The surface is barrren before colonization and there is absence of soil at the starting of the process.
2) Secondary succession, where a previously occupied area becomes recolonised by other living organism. The recolonization is usually due to environmental disturbances e.g. deforestation, flood, earthquake etc. that must have wiped out the previously existing species. In this case, SOIL is already present which makes it easier for recolonization to occur.
